Seating Mechanism and Chair

ABSTRACT

A seating mechanism according to the present invention includes: a support provided on a holder; a seat plate provided pivotably in a substantially vertical direction around the support; and two control portions that are provided with the support therebetween, and apply, when a vertical force is applied to the seat plate, a resisting force against the vertical force to the seat plate. A chair according to the present invention includes the seating mechanism placed on a leg.

TECHNICAL FIELD

The present invention relates to a seating mechanism and a chair.

BACKGROUND ART

A general chair has a structure intended for easy seating. For a chair having a backrest, for example, a user tends to sit thereon with his/her back in contact with the backrest. In this case, the user tends to sit with the center of gravity shifted backward. If the user sits at a desk in such a posture, the user stoops with his/her back bent and the abdomen compressed, and supports the forward-tilted head with muscles of the neck and shoulders, which often causes stiff shoulders.

It is known that good autonomic nerve activity is maintained by balanced activities of sympathetic nerve and parasympathetic nerve. Long hours of deskwork in the stooping posture causes fatigue to build, and the body requires parasympathetic nerve activity, while the deskwork requires sympathetic nerve activity, which needs to forcedly strain sympathetic nerve. This unbalances the sympathetic nerve activity and the parasympathetic nerve activity, causing an increase in stress (excessive strain of sympathetic nerve).

In order to solve this problem, the inventor has proposed a seating device described in Patent Document 1. The seating device is placed on a seat surface of a chair, a seat plate is supported rotatably by a fulcrum member provided on a lower surface of the seat plate and elastically supported upward around the fulcrum member by an elastic member provided on a lower surface of a one-side free end of the seat plate. With the seating device, a user can sit on the seat plate with the center of gravity shifted forward to press the one-side free end of the seat plate against a resilient force of the elastic member during deskwork that requires enhanced sympathetic nerve activity. This allows promotion of normal sympathetic nerve activity.

[Patent Document 1] Japanese Patent Laid-Open No. 11-244099

DISCLOSURE OF THE INVENTION

In recent years, reductions in physical function due to various stresses or changes in lifestyle have been prominent, or various distortions or disorders in the body have been increasing partly due to the reductions in physical function. Thus, it has been desired to promote normal autonomic nerve activity, and also establish effective and general preventive and corrective methods of the distortions or disorders.

On the other hand, medicines or treatment methods such as periodic manipulation have been taken in order to eliminate the inconvenience, which requires efforts, time and expenses. Thus, more convenient preventive and corrective methods have been desired.

The present invention is achieved in view of such circumstances, and has an object to provide a seating mechanism and a chair that can prevent and correct various distortions or disorders in the body more effectively, generally, and conveniently than conventional ones.

In order to solve the above described problem, the inventor has diligently studied and found that maintaining a posture like standing while sitting besides maintaining the state of sitting with the center of gravity shifted forward allows various muscles in the body to be maintained under proper strain, and completed the present invention.

Specifically, a seating mechanism according to the present invention includes: a support provided on a holder; a seat plate provided pivotably in a substantially vertical direction around the support; and two control portions that are provided with the support therebetween, and apply, when a vertical force is applied to the seat plate, a resisting force against the vertical force to the seat plate.

Specifically, the two control portions preferably includes a first control portion placed forward of the support in a seating direction, and a second control portion placed backward of the support in the seating direction.

More specifically, it is preferable that the first control portion applies a substantially vertically upward resisting force to the seat plate, and the second control portion applies a substantially vertically downward resisting force to the seat plate. In other words, the first control portion and the second control portion are not limited as long as the first control portion resists compression and the second control portion resists pulling.

In the seating mechanism thus configured, the seat plate is provided pivotably around the support provided on the holder. Thus, the support serves as a fulcrum by the principle of a lever to tilt the seat plate according to load balance of a user with respect to the support.

Specifically, when the user sets the seating mechanism at a level appropriate for his/her height and sits thereon, with the center-of-gravity line of the user placed slightly backward of the support, the seat plate is tilted so as to push down a back portion in the seating direction, thereby allowing an easy posture. On the other hand, when the user sits with the center of gravity shifted forward so that the toes (strictly, metatarsophalangeal (MP) joints) are placed on a floor surface, the seat plate is substantially horizontal. When the femurs are moved so that the heels are placed on the floor surface with the center of gravity shifted slightly forward, the knee joints are lowered to push down a front portion of the seat plate. Thus, the seat plate is tilted forward, and the user leans forward.

Thus, the vertically upward force against the vertically downward force (the load of the user) is applied to the front portion of the seat plate by the control portion (the first control portion) placed forward of the support, and the vertically downward force against a vertically upward raising force is applied to the back portion of the seat plate by the control portion (the second control portion) placed backward of the support. Thus, a force returning the seat plate to an initial state (for example, a substantially horizontal state) is applied to the entire seat plate.

For maintaining the forward tilt of the seat plate and the forward leaning posture of the user, it is necessary to maintain extension of the spine, and simultaneously properly strain multiple muscle groups in the body including antigravity muscles so as to resist the forces applied by the first and second control portions and returning the seat plate. Thus, the user simply sits on the seating mechanism of the present invention so as to maintain the forward leaning posture, thereby preventing stooping of the spine or a poor sitting posture, and effectively preventing weakening of muscle groups in the body.

It is preferable that the first control portion is provided to previously urge the seat plate vertically upward, and the second control portion is provided to previously urge the seat plate vertically downward.

In this case, the vertically upward force and the vertically downward force are applied to the front and back portions, respectively, of the seat plate in an initial state before sitting. Thus, when the user sits, muscle forces, that is, loads for muscles groups are increased required for maintaining the forward tilt of the seat plate and the forward leaning posture of the user. Therefore, the various muscle groups are trained more effectively.

Conversely, displacement of the seat plate can be reduced in obtaining loads for muscle groups of the same order as loads when the seat plate is not previously urged. Thus, movements of the seat plate and the first and second control portions are reduced to increase durability.

Further, it is preferable that the seat plate has a protruding portion provided forward of the support in the seating direction, more preferably at a front end. The protruding portion includes a portion slightly raised from the seat plate besides a clear protruding portion, and preferably causes no pain in the back sides of the thighs of the user when in contact therewith.

Thus, the thighs of the user are supported in contact with the protruding portion. When the femurs are moved so that the heels are placed on the floor surface to lower the knee joints as described above, the protruding portion serves as a point of application of the vertically downward force to push down the front portion of the seat plate. The protruding portion also serves as a fulcrum of the movements of the femurs to move the hip joints upward by the principle of a lever. These movements cause extension of the hip joints, and facilitate proper strain of extensor and flexor muscle groups of the lower thighs.

Further, the forces can be concentrated on the protruding portion, thereby preventing forces caused by strain of muscles of the user from being spread over a large area of the seat plate, and facilitating pushing down the front portion of the seat plate.

Further, it is more preferable that the support is provided to extend across the width of the seat plate. This facilitates definition of a fore-aft direction and thus a seating direction of the seat plate with the support, and facilitates effective arrangement of the two control portions (the first and second control portions) in the front and back with the support therebetween.

Further, it is more preferable that a fixing portion is provided in a protruding manner on the holder closer to an edge than the second control portion in the seating direction.

Thus, even if the center-of-gravity line is placed backward of the support in the seating direction to tilt the seat plate backward immediately after the user sits, the fixing portion and the seat plate interfere with each other to prevent excessive backward tilt. This allows forward tilt of the seat plate, and prevents unstable backward leaning of the body of the user, facilitating the user's shifting to a forward leaning posture.

Further, the two control portions may be elastic bodies and/or cylinder devices. The elastic body includes, for example, various springs or rubber, and the cylinder device includes, for example, a pneumatic or hydraulic cylinder or a cylindrical damper.

Further, the support is preferably.provided so that the position thereof in the seating direction is adjustable. This allows adjustment of a relative placement of the center-of-gravity position in a sitting state and the support that functions as the fulcrum according to the user's figure or the like.

A chair according to the present invention includes the seating mechanism according to the present invention and effectively functions, and includes the seating mechanism according to the present invention and a leg on which the seating mechanism is placed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a preferred embodiment of a seating mechanism and a chair including the seating mechanism according to the present invention;

FIG. 2 is a front view of the seating mechanism and the chair in FIG. 1;

FIG. 3 is a back view of the seating mechanism and the chair in FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1; and

FIG. 5 is a schematic side view of another embodiment of a seating mechanism and a chair including the seating mechanism according to the present invention, with a person sitting thereon.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the present invention will be described in detail. The same components are denoted by the same reference numerals, and overlapping descriptions will be omitted. Positional relationships between upper and lower and right and left are as shown, except where specifically noted. Further, the dimension ratio of the drawings is not limited to the shown one.

FIG. 1 is a schematic perspective view of a preferred embodiment of a seating mechanism and a chair including the seating mechanism according to the present invention. FIGS. 2 and 3 are front and back views of the seating mechanism and the chair in FIG. 1. Further, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1.

A chair 10 includes a seating device 1 (a seating mechanism) placed on a leg 2. The seating device 1 mainly includes a seat plate 11 formed of a substantially rectangular plate member and a base plate 12 (a holder) formed of a plate member of substantially the same shape. A support 13 having a substantially trapezoidal section is provided between the seat plate 11 and the base plate 12 so as to extend across the width of the base plate 12. A lower wall surface of the seat plate 11 abuts an upper end of the support 13.

The support 13 is provided so that a fore-aft position in a seating direction (a direction horizontally perpendicular to the support 13 in the drawings) is adjustable. A mechanism for the adjustment includes, for example, a known gear type movable rail (not shown) provided on the base plate 12, or a plurality of fitting grooves (not shown) formed on the base plate 12 in which the support 13 is fitted.

A plurality of coil springs 14 (generally, a first control portion) are secured on an end (a front end) of the base plate 12 forward of the support 13 in the seating direction, along an edge of the base plate 12. These coil springs 14 abut the lower wall surface of the seat plate 11 in a compressed manner with the seat plate 11 placed thereon at rest. Upper ends of the coil springs 14 may or may not be secured to the lower wall surface of the seat plate 11.

A plurality of coil springs 15 (generally, a second control portion) are secured on an end (a back end) of the base plate 12 backward of the support 13 in the seating direction, along an edge of the base plate 12. These coil springs 15 are secured on the lower wall surface of the seat plate 11 in an extended manner with the seat plate 11 placed thereon at rest.

A fixing portion 17 having a substantially trapezoidal section is provided on the edge of the base plate 12 backward of the coil springs 15 so as to extend across the width of the base plate 12. The fixing portion 17 is lower in height than the support 13, and the seat plate 11 is placed with a certain space from the fixing portion 17 when the seat plate 11 is placed on the support 13 at rest.

A protruding portion 16 having a substantially trapezoidal section gently raised is provided in a protruding manner on an upper surface of the front end of the seat plate 11 in the seating direction (more specifically, the position where the plurality of coil springs 14 are provided) so as to extend across the width of the base plate 12.

The leg 2 includes a leg receiver 21 secured to substantially the center of the lower wall surface of the base plate 12, an extendable rod 23 having an upper end circumferentially rotatably connected to the leg receiver 21, and a hydraulic cylinder 24 to which the other end of the extendable rod 23 is connected. A seat height adjustment lever 22 pivotable, for example, in a vertical direction is provided on a peripheral wall of the extendable rod 23, and the lever is moved to drive the hydraulic cylinder 24 and extend the extendable rod 23. The hydraulic cylinder 24 is secured to a leg base having a plurality of legs 25.

Operations of the seating device 1 and the chair including the seating device thus configured will be described in detail with reference to FIG. 5. FIG. 5 is a schematic side view of another preferred embodiment of a seating mechanism and a chair including the seating mechanism according to the present invention, with a person sitting thereon. A chair 30 is configured similarly to the chair 10 except that a cushion 3 is provided on an upper surface of the seat plate 11 of the seating device 1.

When sitting on the chair 30, a user H operates the seat height adjustment lever 22 to adjust the length of the extendable rod 23 with the hydraulic cylinder 24 according to the height of the user H. Specifically, it is preferable that the user stands in front of the chair 30, and adjusts the length of the extendable rod 23 so that a vertical level of the seat plate 11 is, for example, 3 to 10 cm higher than the poples (areas with wrinkles on the back of the knees). It is also preferable that the height of the seat plate 11 is set so that the toes (MP joints) are placed on the floor surface when the seat plate 11 is substantially horizontal with the user sitting thereon as described later.

Further, a fore-aft position of the support 13 is adjusted that functions as a fulcrum of tilt of the seat plate 11. Specifically, the position of the support 13 is preferably adjusted so that the support 13 is placed near the greater trochanters (top ends of the femurs) of the user.

When the user H sits in this state, the center-of-gravity line of the user H is generally placed backward of the support 13 to tilt the seat plate 11 backward, though the rear end of the seat plate 11 interferes with the fixing portion 17. Thus, when the user H sits, the seat plate 11 is supported by the fixing portion 17 to substantially horizontally maintain the seat surface, that is, the femurs of the user H and place the toes (MP joints) on the floor surface. This sitting posture is relatively easy with the pelvis tilted slightly backward.

In this posture, areas of about one third of the entire length of the femurs from distal ends of the femurs generally abut the protruding portion 16. When the femurs are moved so that the heels are placed on the floor surface in this state, the knee joints positioned at the distal ends of the femurs are lowered, and the protruding portion 16 serve as a point of application of a vertically downward force to push down the front end of the seat plate 11. Simultaneously, the protruding portion 16 also serves as a fulcrum of the movements of the femurs to move the hip joints at proximal ends of the femurs upward. These movements cause anatomical extension of the hip joints.

The extension of the hip joints provides proper strain of extensor and flexor muscle groups of the lower thighs, and contraction of gluteus maximus muscles and hamstring muscles in the hip joints. Further, iliopsoas muscles or the like as one of the flexor muscle groups also contract for securing the joints.

Thus, the forward tilt of the seat plate 11 moves the center of gravity of the user H forward, tilts the pelvis more forward than when the seat plate 11 is substantially horizontal, and extends the spine, thereby causing the user H to sit in a slightly forward leaning posture. As the user H becomes accustomed to sitting on the chair 30, the user can sit in such a forward leaning posture immediately after sitting thereon.

With the seat plate 11 tilted forward, the coil springs 14 provided under the front end of the seat plate 11 apply a vertically upward force to the front end of the seat plate 11 so as to resist compression by the load of the user H. Thus, the seat plate 11 is pushed up to a position where the load of the user H and the resisting force of the coil spring 14 are balanced, so as to return to the horizontal state.

Besides, with the seat plate 11 tilted forward, the coil springs 15 provided under the back end of the seat plate 11 are extended as the seat plate 11 is raised, and applies a vertically downward force to the back end of the seat plate 11 so as to resist the extension. Then, the support 13 functions as a fulcrum of a lever to further raise the front end of the seat plate 11. Thus, the seat plate 11 more effectively moves to return to the horizontal state than by only the resisting force of the coil springs 14.

Thus, only with the resisting force of the coil springs 14, the pulling force of the coil springs 15 further raise the front end of the seat plate 11 (see the arrow Y in FIG. 5) even if the user H can maintain the forward leaning posture to some degree by his/her load. The user H thus needs to further strain muscles required for maintaining the forward leaning posture.

Specifically, since the resisting force of the coil springs 14 and the pulling force of the coil springs 15 causes the seat plate 11 to strongly return to the horizontal direction, relaxing muscles of the whole body including the lower limbs easily causes the seat plate 11 to return to the initial horizontal state. This causes the backward tilt of the pelvis and thus provides the initial easy sitting state.

Thus, proper and continuous or intermittent strain of extensor and flexor muscle groups of the lower thighs (musculus triceps surae) is required for maintaining the forward tilt of the seat plate 11 and the forward leaning posture of the user H. Maintaining such muscle strain prevents weakening of muscle forces, and facilitates return of venous blood and lymph by the action of muscle pump, thereby preventing edema in the lower thighs and tightening the ankles.

Proper strain of the medial rotator group including musculus tensor fasciae latae of the hip joints, the lateral rotator group including piriformis muscle, and the extensor and flexor muscles of the hip joints is required for maintaining the forward tilt of the seat plate 11 and the forward leaning posture of the user H since the hip joints easily come into contact with the protruding portion in a position between medial and lateral rotation. Maintaining such muscle strain facilitates development of the muscle forces, and thus effectively prevents disorders in the hip joints.

Further, the forward tilt of the seat plate 11 and the forward leaning posture of the user H are maintained to cause the femurs and the tibias to return to a physiologically proper state (a physiological line) inherent to a human, thereby correcting knock-knees or bow-legs.

Further, proper and continuous or intermittent strain of hamstring muscles (biceps femoris muscle, musculus semitendinosus, and musculus semimembranosus) that extend the hip joints and originate from tuber ischiadicum is required for maintaining the forward tilt of the seat plate 11 and the forward leaning posture of the user H. Maintaining such muscle strain causes proper strain of quadriceps femoris that is flexor muscle of the hip joint. This prevents muscle atrophy of the thighs, thereby preventing reduction in antigravity muscle force of the thighs.

Further, maintaining the forward tilt of the seat plate 11 and the forward leaning postures of the user H with the user H sitting on the chair 30 makes it difficult for the user H to cross the legs or place the lower limbs in other unnatural positions, thereby preventing and correcting distortion of the body.

Maintaining the forward tilt of the seat plate 11 and the forward leaning posture of the user H maintains proper and continuous or intermittent strain of gluteus maximus muscle, gluteus medius muscle relating to lateral rotation, gluteus minimus muscle relating to medial and lateral rotation of extensor muscle groups of the hip joints in the pelvis. This prevents muscle atrophy and prevents weakening of muscle forces. Besides, more lifted buttocks can be obtained for beauty. Further, for a user H having anal fistula or hemorrhoid, the affected area is prevented from being directly pressed on the seat surface of the seat plate 11 since pelvic floor muscles also strain besides the gluteus maximus muscle, gluteus medius muscle, and gluteus minimus muscle.

Further, for maintaining the forward tilt of the seat plate 11 and the forward leaning posture of the user H, coordinated muscle strain of erector muscle group of the back trunk, abdomen muscle group of the front trunk, and iliopsoas muscle group extending from the spine to the lesser trochanter maintains the ilium tilted forward to extend the spine as in a natural standing posture. This prevents reduction in force of the iliopsoas muscle that is one of the important muscles among the antigravity muscles. This prevents lower-back pain due to forward, backward and lateral curvature of the lumbar spine. The prevention of weakening of the antigravity muscles effectively prevents persons in late middle age or old age from being bedridden.

The physiologically proper state (the physiological line) of the spine is generated to prevent a stoop to ease breathing in the chest. In addition, unnatural shoulder strain or forward and backward bending of the neck, thereby preventing stiff shoulder or neck. Further, the posture forming the physiological line prevents unnecessary near point adjustment of the eyes, thereby preventing false myopia or eye strain. Further, more lifted breasts can be obtained for beauty.

Proper strain of the abdominal muscles also prevents disorders such as splanchnoptosis due to reduction in muscle force. Further, a thinner waist can be obtained for beauty.

The seating device 1 and the chair 10 or 30 including the seating device 1 produce the various effects as described above, thereby preventing and correcting various distortions or disorders in the body more effectively, generally, and conveniently.

The coil springs 14 abut the lower wall surface of the seat plate 11 in the compressed manner with the seat plate 11 placed thereon at rest to previously urge the front portion of the seat plate 11 vertically upward. This further causes the seat plate 11 to return to the substantially horizontal state, thereby increasing the load for muscle groups required for the user H to maintain the forward leaning posture, and thus increasing the above described various effects.

The coil springs 15 are secured on the lower wall surface of the seat plate 11 in the extended manner with the seat plate 11 placed thereon at rest to previously urge the back portion of the seat plate 11 vertically downward. This further causes the seat plate 11 to return to the substantially horizontal state, thereby increasing the load for muscle groups required for the user H to maintain the forward leaning posture, and thus increasing the above described various effects.

Since the coil springs 14 and 15 are provided to previously urge the seat plate 11, muscle loads of the same order as loads when the seat plate 11 is not thus urged can be applied to the user H with smaller displacement. This reduces movements of the seat plate 11 and the coil springs 14 and 15 to increase durability in repeated use.

The present invention is not limited to the above described embodiment, and variations can be made without changing the gist of the invention. For example, elastic bodies such as other springs or rubber, or a pneumatic or hydraulic cylinder or a cylindrical damper may be used instead of the coil springs 14 and 15. Further, the coil springs 14 and 15 or other first and second control portions may be, for example, connected and integrated. Further, the number and arrangement of coil springs 14 and 15 are not limited to the shown example, and a plurality of coil springs may be unitized. The seat plate 11 may not be previously urged.

Further, the spring constant, that is, the resisting forces of the coil springs 14 and 15 may be adjusted according to the weight, figure, and muscle force of the user H. Particularly, the coil springs 15 placed on the back side are preferably adjustable. In this case, the coil springs 14 and 15 are removably provided on the base plate 12 and/or the seat plate 11 to facilitate replacement and enhance maintainability. One ends of the coil springs 14 and 15 may be secured to the leg 2 without providing the base plate 12. In this case, the leg 2 functions as a holder. This reduces the number of components, and further enhances maintainability.

Further, a backrest, a handrail, or an armrest may be provided. The protruding portion 16 is preferably provided, though not essential. The protruding portion 16 may not be integrally extended but, for example, may be divided into two parts in positions in contact with right and left thighs. Also, the seat plate 11 may be circular to form a circular chair 10 or 30.

The seating mechanism and the chair including the seating mechanism according to the present invention includes the above described support and the two control portions, and can prevent and correct various distortions or disorders in the body more effectively, generally, and conveniently than conventional ones. Thus, the device can be widely used for treatment of the body and beauty. 

1. A seating mechanism comprising: a support provided on a holder; a seat plate provided pivotably in a substantially vertical direction around said support; and two control portions that are provide with said support therebetween, and apply, when a vertical force is applied to said seat plate, a resisting force against said vertical force to said seat plate.
 2. The seating mechanism according to claim 1, wherein said two control portions includes a first control portion placed forward of said support in a seating direction, and a second control portion placed backward of said support in the seating direction.
 3. The seating mechanism according to claim 2, wherein said first control portion applies a vertically upward resisting force to said seat plate, and said second control portion applies a vertically downward resisting force to said seat plate.
 4. The seating mechanism according to claim 2, wherein said first control portion is provided to previously urge said seat plate vertically upward, and said second control portion is provided to previously urge said seat plate vertically downward.
 5. The seating mechanism according to claim 1, wherein said seat plate has a protruding portion provided forward of said support in the seating direction.
 6. The seating mechanism according to claims 1, wherein said support is provided to extend across the width of said seat plate.
 7. The seating mechanism according to claims 2, wherein a fixing portion is provided in a protruding manner on said holder closer to an edge than said second control portion in said seating direction.
 8. The seating mechanism according to claims 1, wherein said two control portions are elastic bodies and/or cylinder devices.
 9. The seating mechanism according to any one of claims 1, wherein said support is provided so that the position thereof in said seating direction is adjustable.
 10. A chair comprising: a seating mechanism according to claims 1; and a leg on which said seating mechanism is placed. 